The invention concerns a method for transferring a continuously arriving web, such as a paper or cardboard web, from a finished roll on a new core rotating at the travel speed of the web, and a drum winder for carrying out said method.
A method of transferring a continuously arriving web and corresponding drum winder are previously known from the U.S. Pat. No. 4,445,646. The transfer strip is produced there in the center of the web by two parallel cuts. The transfer strip is simultaneously perforated through an incision which occurs approximately crosswise to the direction of web travel, but the strip continues to be connected with the web leader. As the transfer strip approaches the gap between the drum and the new core, the blades serving to produce the strip advance in the direction of the respective adjacent web edge so that the remaining web will be severed. As the transfer strip passes through the gap between the drum and the new core, a compressed air jet impinges on the web and this is supposed to completely sever the transfer strip in the perforated area from the web leader and guide it around the new core. Upon completed transfer of the web leader to the new core, the finished roll is removed from the drum and the new core takes its place. The prior winding method is suitable only for webs having a low basis weight and/or low strength. For webs having a high basis weight and/or high strength, a compressed air jet is not sufficiently effective to dependably separate the transfer strip from the advancing web.
The German Patent Disclosure No. 27 21 883 suggest to sever the transfer strip leaving the gap with the aid of a knife, but this requires the knife to engage the web looping around the drum entailing necessary damage to the drum surface. An unsuccessful transfer process results in a considerable web loss because a new transfer attempt can be initiated only after the knives of the cutoff device have returned to their home position. In the meantime, however, the web approaching the drum at high speed continues to wind on the roll. Thus, once the roll change has been completed, several web layers must be peeled off the finished roll so as to remove the web area which was cut up during the unsuccessful transfer attempt.